1. Field of the Invention
The present invention relates to an Air Core(trademark) cooking vessel, specifically, to a cooking vessel having a double-layered structure that preserves heat and traps moisture during cooking.
2. Description of the Related Art
Various types of cooking vessel are known and used in a kitchen. Such cooking vessel is made of one or more layers of stainless steel and has a single-layered bottom. The single layered bottom is good for directly transmitting heat to the food contained in the vessel, but also causes burning of the food when carefully not attended to.
To solve the above problems, a cooking vessel having a double-layered structure has been proposed for preventing burnt food and to improve food flavor. One such ideas is published in Korean Utility Laid-Open Publication No. 85-7307, which teaches that paraffin is injected between a space provided by a double-layered structure and an air hole is established thereon.
Moreover, a pot of a double-layered structure and a pot having a double-layered structure into which a working fluid is injected are taught by Japanese Laid-Open Publication No. 56-169825.
Instead of charging the space with paraffin, a structure into which a fluid of heat-medium is injected and sealed is disclosed in Korean Laid-Open Publication No. 97-4035.
In such pots having the above-mentioned structures of the related arts, the gap between the double-layer are filled with heat media to provide even-heat distribution and to save heat energy. Unfortunately, the structures of the related arts are filled with the heat medium substances and have to be sealed to prevent the substances from leaking out, resulting in the difficulties in manufacturing the cookware.
Accordingly, the present invention is directed to a cooking vessel that substantially obviates one, or more of the problems due to limitations and disadvantages of the related art.
The object of the present invention is to provide a cooking vessel having a double-layered structure, which provide even heat distribution and preserves heat for a longer period of time.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a cooking vessel comprises an inner shell having an open region having a bottom surface which extends upwardly to terminate at a top flange, a portion of the top flange forming an inner rim and an outer rim, the inner rim having a radius less than the radius of the outer rim, the outer rim formed substantially above the inner rim; an outer shell having an open region having a bottom surface which extends upwardly to terminate at an outwardly projecting bottom flange, the bottom flange having a length less than the length of the top flange; an inner space formed in an area between the inner shell and the outer shell and at least partially contains a heat conduction medium, the inner space formed by disposing the inner shell into the open region of the outer shell, wherein outer edges of the top flange is interlocked to outer edges of the bottom flange and substantially flattened to hermetically seal the inner space.
According to one aspect of the present invention, the wall space between the outer and inner shells contains air as its primary heat conduction medium. Alternatively, the wall space defined by the outer and inner shells contains a chemical, such as silicon oil, as its primary heat conduction medium.
According to another aspect of the present invention, a heat transfer plate is affixed to and in contact with an outer bottom surface of the outer shell. Preferably, the heat-transfer plate is bonded to the base of the vessel by high impact. By bonding the plate by high impact, the vessel is more durable than if it was affixed by a brazing method because water that can cause rust and damage the cooking vessel is kept out of the area where the heat transfer plate is affixed.
In addition, the cooking vessel comprises an inner lid adapted to cover an open region of the inner shell and a portion of the inner rim. The inner lid comprises a disk having a diameter sufficiently large to cover the opening of the inner shell, and a ring having a flange coupled to the disk and circumferentially covering outer edges of the disk. The disk is preferably made of tempered glass but could also be made of stainless steel, aluminum and aluminum alloy.
The inner rim can also be shaped in a groove-like manner to fit the ring attached to the outer edges of the disk and to trap moisture. When moisture evaporates from cooking, the groove-like inner rim collects a pocket of moisture. The collected moisture acts as a seal, preventing additional moisture and heat from leaving the open region of the inner shell where the food is being cooked.
The flange formed on the bottom portion of the ring slides downward into the open region of the inner shell, and it is another means of ensuring that moisture and heat stay inside the cooking vessel.
Additionally, the cooking vessel comprises an outer lid that fits over the outer rim of the inner shell and the inner lid. The outer and the inner lid define an air gap space therebetween for trapping heat. The air gap, like the inner space, is a way of trapping heat and moisture, and distributing heat evenly and optimally.
Preferably, a means gauging temperature is installed on the outer lid. More preferably, the temperature gauge is affixed on the protruding knob. The temperature gauge informs the user when to turn off the stove and let the cooking vessel utilize the heat trapped in the vessel to finish the cooking.
When the heat conduction medium, such as silicon oil is contained in the wall space defined by vertical cylindrical walls of the outer and inner shells, the amount of silicon oil stored in the wall space is approximately 55 to 75%, and more preferably about 65%, by volume.
According to another aspect of the present invention, the cooking vessel further comprises a guard ring disposed in a lower proximity of the wall space around a circumference of the first heat conduction plate. Preferably, the guard ring has an L-shaped cross section. Alternatively, the guard ring has a U-shaped cross section.
According to another aspect of the present invention, the outer edges of the top flange are first welded to the outer edges of the bottom flange, and then interlocked and substantially flattened to form an interlocking joint. Preferably, the outer edges are welded in a seamless matter to prevent water from entering into the inner space formed in between the inner and outer shell.
According to another aspect of the present invention, the outer edges of the bottom flange is rolled at least one time, at about a 360 degree angle, interlocked with the top flange and substantially flattened to form an interlocking joint.
According to another aspect of the present invention, a pressure control element is installed on the outer shell. Preferably, a pressure relief valve is installed near one of the handles.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.